In electric vehicles such as electric cars, drive devices to be driven by power of batteries are mounted. Of the drive devices, in particular, a drive device for directly driving a wheel is called “in-wheel motor”. The types of driving of the in-wheel motor include a gear reduction type provided with a reducing mechanism and a direct drive type not provided with a reducing mechanism. The in-wheel motor of the gear reduction type can easily output torque necessary when an electric vehicle starts and climbs (ascends a hill), but a friction loss occurs in the reducing mechanism. On the other hand, the in-wheel motor of the direct drive type can prevent the friction loss, but the torque that can be output is relatively small. When an electric vehicle starts or climbs, relatively large torque is necessary, but the traveling speed of the vehicle is relatively low. When the electric vehicle cruises on a flat road, on the other hand, necessary torque is small, but the traveling speed of the vehicle is relatively high. Thus, for example, Patent Literature 1 discloses an in-wheel motor including a transmission mechanism.